In a first for Yamaha, they've released an app that looks pretty damn cool! Visual Performer is a MIDI-aware visualization app.
Yamaha's Visual Performer is a App for iPad/iPhone/iPod touch which you can express your playing in graphical animation.
Features:• Graphic animation appears synchronized with the playing by the MIDI instrument (WiFi or a cable is required)
• 10 types of graphic animations and the projected image by iOS device's camera
• Customize your original animation by combining with two patterns
• Change the animation pattern during your play by using chain function
• Record your sound and the animation on your iPhone/iPad. *Video format: mov.
• Play with your iPhone/iPad (XY Pad or Virtual keyboard)
• Synchronize with musical playing application on the other iOS device (WiFi is required)
The app is free, but there is a $3 IAP called Special Package. It looks like this could be handy for livening up some of the boring videos I see on YouTube of people just pressing Play in Garageband. Thanks to reader Rafael for pointing this out!
Yamaha has an annoying habit of breaking up their apps by region and language. The one on iTunes Spain is also in English, and it isn't even available in Yamaha's home country of Japan! If you can't use this first link, the second one seems to be a generic European version, but it is also only localized in English. Amusingly iTunes Canada also points to this European version.